The invention is specifically intended for use with conventional cranes having a crane body with a forwardly projecting boom that pivotally moves up and down for positioning purposes during crane operation. The crane body pivotally swings about a substantially vertical axis relative to an undercarriage that typically is movable on endless tracks.
Government regulations now require that many types of heavy equipment be provided with some type of safety apparatus to avoid accidents. As an example, many heavy machines that move during operations must include an intermittent audible alarm at any time they move in reverse, when the operator's view is neither direct nor complete.
In one type of crane, the crane body pivotally carries a forwardly projecting boom of substantial length, and a counter-weight is mounted to the opposite end of the crane body for balance purposes. The operator faces the direction of boom projection, and for this reason has a clear view to avoid most problems involving the boom. However, this type of crane must of necessity pivotally swing about a substantially vertical axis about its undercarriage to position the boom in various places during operation, and the rear end of the crane body may create hazardous problems with respect to objects and persons that come into its path.
This problem has been approached in different manners in the prior art. As an example, barricades have been attached to the crane body which are outside its swing radius. However, this approach substantially increases the width of the entire crane to the point where it is extremely difficult to move.
As another example, separate barricades have been set up around the crane to keep objects and people outside the crane swing area. However, this involves considerable labor to set up and remove the barricades each time the entire crane is moved to a new position.